OCAPI JSONP 19.1

JSONP (JSON with padding) allows a browser page to request data from a
server in a different domain. Normally, a Web API request returns a plain
JSON document, which requires the client to parse the JSON document. There
are some Browser JavaScript cases where it is much more efficient to
respond with JavaScript code instead of with a JSON document. The response
is directly evaluated by the JavaScript interpreter and is not parsed by a
JSONParser. The response, in these cases, is merely a JSON document with a
JavaScript function call wrapped around it.

The Open Commerce API offers the URL request parameter
callback. The value of this parameter is the name of the
JavaScript function that is wrapped around the JSON document.